From patchwork Tue May 10 03:45:58 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baolin Wang X-Patchwork-Id: 12844503 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CC95C433FE for ; Tue, 10 May 2022 03:46:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9F22C6B0073; Mon, 9 May 2022 23:46:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 97BF56B0074; Mon, 9 May 2022 23:46:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 845A46B0075; Mon, 9 May 2022 23:46:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 76CCD6B0073 for ; Mon, 9 May 2022 23:46:33 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 45C1A306E0 for ; Tue, 10 May 2022 03:46:33 +0000 (UTC) X-FDA: 79448446266.27.C750BAF Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by imf15.hostedemail.com (Postfix) with ESMTP id BE6A3A008A for ; Tue, 10 May 2022 03:46:20 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=32;SR=0;TI=SMTPD_---0VCooyJa_1652154385; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VCooyJa_1652154385) by smtp.aliyun-inc.com(127.0.0.1); Tue, 10 May 2022 11:46:26 +0800 From: Baolin Wang To: akpm@linux-foundation.org, mike.kravetz@oracle.com, catalin.marinas@arm.com, will@kernel.org Cc: songmuchun@bytedance.com, tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, arnd@arndb.de, baolin.wang@linux.alibaba.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 1/3] mm: change huge_ptep_clear_flush() to return the original pte Date: Tue, 10 May 2022 11:45:58 +0800 Message-Id: X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: Authentication-Results: imf15.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf15.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.130 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: BE6A3A008A X-Rspam-User: X-Stat-Signature: 6wq6h15iiyhmbbtw99hrwo5yqk91wuxi X-HE-Tag: 1652154380-826113 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: It is incorrect to use ptep_clear_flush() to nuke a hugetlb page table when unmapping or migrating a hugetlb page, and will change to use huge_ptep_clear_flush() instead in the following patches. So this is a preparation patch, which changes the huge_ptep_clear_flush() to return the original pte to help to nuke a hugetlb page table. Signed-off-by: Baolin Wang Acked-by: Mike Kravetz Reviewed-by: Muchun Song --- arch/arm64/include/asm/hugetlb.h | 4 ++-- arch/arm64/mm/hugetlbpage.c | 12 +++++------- arch/ia64/include/asm/hugetlb.h | 4 ++-- arch/mips/include/asm/hugetlb.h | 9 ++++++--- arch/parisc/include/asm/hugetlb.h | 4 ++-- arch/powerpc/include/asm/hugetlb.h | 9 ++++++--- arch/s390/include/asm/hugetlb.h | 6 +++--- arch/sh/include/asm/hugetlb.h | 4 ++-- arch/sparc/include/asm/hugetlb.h | 4 ++-- include/asm-generic/hugetlb.h | 4 ++-- 10 files changed, 32 insertions(+), 28 deletions(-) diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h index 1242f71..616b2ca 100644 --- a/arch/arm64/include/asm/hugetlb.h +++ b/arch/arm64/include/asm/hugetlb.h @@ -39,8 +39,8 @@ extern pte_t huge_ptep_get_and_clear(struct mm_struct *mm, extern void huge_ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep); #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -extern void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep); +extern pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep); #define __HAVE_ARCH_HUGE_PTE_CLEAR extern void huge_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep, unsigned long sz); diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index cbace1c..ca8e65c 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -486,19 +486,17 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm, set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot)); } -void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) +pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { size_t pgsize; int ncontig; - if (!pte_cont(READ_ONCE(*ptep))) { - ptep_clear_flush(vma, addr, ptep); - return; - } + if (!pte_cont(READ_ONCE(*ptep))) + return ptep_clear_flush(vma, addr, ptep); ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize); - clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig); + return get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig); } static int __init hugetlbpage_init(void) diff --git a/arch/ia64/include/asm/hugetlb.h b/arch/ia64/include/asm/hugetlb.h index 7e46ebd..65d3811 100644 --- a/arch/ia64/include/asm/hugetlb.h +++ b/arch/ia64/include/asm/hugetlb.h @@ -23,8 +23,8 @@ static inline int is_hugepage_only_range(struct mm_struct *mm, #define is_hugepage_only_range is_hugepage_only_range #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { } diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h index c214440..fd69c88 100644 --- a/arch/mips/include/asm/hugetlb.h +++ b/arch/mips/include/asm/hugetlb.h @@ -43,16 +43,19 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm, } #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { + pte_t pte; + /* * clear the huge pte entry firstly, so that the other smp threads will * not get old pte entry after finishing flush_tlb_page and before * setting new huge pte entry */ - huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); + pte = huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); flush_tlb_page(vma, addr); + return pte; } #define __HAVE_ARCH_HUGE_PTE_NONE diff --git a/arch/parisc/include/asm/hugetlb.h b/arch/parisc/include/asm/hugetlb.h index a69cf9e..25bc560 100644 --- a/arch/parisc/include/asm/hugetlb.h +++ b/arch/parisc/include/asm/hugetlb.h @@ -28,8 +28,8 @@ static inline int prepare_hugepage_range(struct file *file, } #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { } diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h index 6a1a1ac..8a5674f 100644 --- a/arch/powerpc/include/asm/hugetlb.h +++ b/arch/powerpc/include/asm/hugetlb.h @@ -43,11 +43,14 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm, } #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { - huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); + pte_t pte; + + pte = huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); flush_hugetlb_page(vma, addr); + return pte; } #define __HAVE_ARCH_HUGE_PTEP_SET_ACCESS_FLAGS diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h index 32c3fd6..f22beda 100644 --- a/arch/s390/include/asm/hugetlb.h +++ b/arch/s390/include/asm/hugetlb.h @@ -50,10 +50,10 @@ static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr, set_pte(ptep, __pte(_SEGMENT_ENTRY_EMPTY)); } -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long address, pte_t *ptep) +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long address, pte_t *ptep) { - huge_ptep_get_and_clear(vma->vm_mm, address, ptep); + return huge_ptep_get_and_clear(vma->vm_mm, address, ptep); } static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma, diff --git a/arch/sh/include/asm/hugetlb.h b/arch/sh/include/asm/hugetlb.h index ae4de7b..e727cc9 100644 --- a/arch/sh/include/asm/hugetlb.h +++ b/arch/sh/include/asm/hugetlb.h @@ -21,8 +21,8 @@ static inline int prepare_hugepage_range(struct file *file, } #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { } diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h index 53838a1..b50aa6f 100644 --- a/arch/sparc/include/asm/hugetlb.h +++ b/arch/sparc/include/asm/hugetlb.h @@ -21,8 +21,8 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep); #define __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep) +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { } diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h index 896f341..a57d667 100644 --- a/include/asm-generic/hugetlb.h +++ b/include/asm-generic/hugetlb.h @@ -84,10 +84,10 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm, #endif #ifndef __HAVE_ARCH_HUGE_PTEP_CLEAR_FLUSH -static inline void huge_ptep_clear_flush(struct vm_area_struct *vma, +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { - ptep_clear_flush(vma, addr, ptep); + return ptep_clear_flush(vma, addr, ptep); } #endif From patchwork Tue May 10 03:45:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baolin Wang X-Patchwork-Id: 12844504 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7A29C433FE for ; Tue, 10 May 2022 03:46:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7359D6B0074; Mon, 9 May 2022 23:46:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6E30D6B0075; Mon, 9 May 2022 23:46:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5D1376B0078; Mon, 9 May 2022 23:46:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 4FA516B0074 for ; Mon, 9 May 2022 23:46:36 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 2B6842105D for ; Tue, 10 May 2022 03:46:36 +0000 (UTC) X-FDA: 79448446392.08.FE9CCDE Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by imf31.hostedemail.com (Postfix) with ESMTP id 20D2E20082 for ; Tue, 10 May 2022 03:46:13 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=32;SR=0;TI=SMTPD_---0VCobrrD_1652154387; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VCobrrD_1652154387) by smtp.aliyun-inc.com(127.0.0.1); Tue, 10 May 2022 11:46:28 +0800 From: Baolin Wang To: akpm@linux-foundation.org, mike.kravetz@oracle.com, catalin.marinas@arm.com, will@kernel.org Cc: songmuchun@bytedance.com, tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, arnd@arndb.de, baolin.wang@linux.alibaba.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Date: Tue, 10 May 2022 11:45:59 +0800 Message-Id: X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: Authentication-Results: imf31.hostedemail.com; dkim=none; spf=pass (imf31.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.130 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 20D2E20082 X-Stat-Signature: grfgs1nd4eb7t7w9yg7g8eeux4fuebjr X-HE-Tag: 1652154373-190736 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On some architectures (like ARM64), it can support CONT-PTE/PMD size hugetlb, which means it can support not only PMD/PUD size hugetlb: 2M and 1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page size specified. When migrating a hugetlb page, we will get the relevant page table entry by huge_pte_offset() only once to nuke it and remap it with a migration pte entry. This is correct for PMD or PUD size hugetlb, since they always contain only one pmd entry or pud entry in the page table. However this is incorrect for CONT-PTE and CONT-PMD size hugetlb, since they can contain several continuous pte or pmd entry with same page table attributes. So we will nuke or remap only one pte or pmd entry for this CONT-PTE/PMD size hugetlb page, which is not expected for hugetlb migration. The problem is we can still continue to modify the subpages' data of a hugetlb page during migrating a hugetlb page, which can cause a serious data consistent issue, since we did not nuke the page table entry and set a migration pte for the subpages of a hugetlb page. To fix this issue, we should change to use huge_ptep_clear_flush() to nuke a hugetlb page table, and remap it with set_huge_pte_at() and set_huge_swap_pte_at() when migrating a hugetlb page, which already considered the CONT-PTE or CONT-PMD size hugetlb. Signed-off-by: Baolin Wang Reviewed-by: Muchun Song Reviewed-by: Mike Kravetz --- include/linux/hugetlb.h | 11 +++++++++++ mm/rmap.c | 24 ++++++++++++++++++------ 2 files changed, 29 insertions(+), 6 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 306d6ef..9f71043 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1093,6 +1093,17 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr pte_t *ptep, pte_t pte, unsigned long sz) { } + +static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) +{ + return ptep_get(ptep); +} + +static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, + pte_t *ptep, pte_t pte) +{ +} #endif /* CONFIG_HUGETLB_PAGE */ static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/mm/rmap.c b/mm/rmap.c index 94d6b24..4e96daf 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1926,13 +1926,15 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, break; } } + + /* Nuke the hugetlb page table entry */ + pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); } else { flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); + /* Nuke the page table entry. */ + pteval = ptep_clear_flush(vma, address, pvmw.pte); } - /* Nuke the page table entry. */ - pteval = ptep_clear_flush(vma, address, pvmw.pte); - /* Set the dirty flag on the folio now the pte is gone. */ if (pte_dirty(pteval)) folio_mark_dirty(folio); @@ -2017,7 +2019,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, pte_t swp_pte; if (arch_unmap_one(mm, vma, address, pteval) < 0) { - set_pte_at(mm, address, pvmw.pte, pteval); + if (folio_test_hugetlb(folio)) + set_huge_pte_at(mm, address, pvmw.pte, pteval); + else + set_pte_at(mm, address, pvmw.pte, pteval); ret = false; page_vma_mapped_walk_done(&pvmw); break; @@ -2026,7 +2031,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, !anon_exclusive, subpage); if (anon_exclusive && page_try_share_anon_rmap(subpage)) { - set_pte_at(mm, address, pvmw.pte, pteval); + if (folio_test_hugetlb(folio)) + set_huge_pte_at(mm, address, pvmw.pte, pteval); + else + set_pte_at(mm, address, pvmw.pte, pteval); ret = false; page_vma_mapped_walk_done(&pvmw); break; @@ -2052,7 +2060,11 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, swp_pte = pte_swp_mksoft_dirty(swp_pte); if (pte_uffd_wp(pteval)) swp_pte = pte_swp_mkuffd_wp(swp_pte); - set_pte_at(mm, address, pvmw.pte, swp_pte); + if (folio_test_hugetlb(folio)) + set_huge_swap_pte_at(mm, address, pvmw.pte, + swp_pte, vma_mmu_pagesize(vma)); + else + set_pte_at(mm, address, pvmw.pte, swp_pte); trace_set_migration_pte(address, pte_val(swp_pte), compound_order(&folio->page)); /* From patchwork Tue May 10 03:46:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baolin Wang X-Patchwork-Id: 12844505 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3357CC433EF for ; Tue, 10 May 2022 03:46:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BC7216B0075; Mon, 9 May 2022 23:46:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B76896B0078; Mon, 9 May 2022 23:46:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A40C16B007B; Mon, 9 May 2022 23:46:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 973676B0075 for ; Mon, 9 May 2022 23:46:43 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 76CF6306E6 for ; Tue, 10 May 2022 03:46:43 +0000 (UTC) X-FDA: 79448446686.15.ED5C679 Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com [115.124.30.57]) by imf23.hostedemail.com (Postfix) with ESMTP id 5D4D714009A for ; Tue, 10 May 2022 03:46:28 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=32;SR=0;TI=SMTPD_---0VCooyL6_1652154389; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VCooyL6_1652154389) by smtp.aliyun-inc.com(127.0.0.1); Tue, 10 May 2022 11:46:30 +0800 From: Baolin Wang To: akpm@linux-foundation.org, mike.kravetz@oracle.com, catalin.marinas@arm.com, will@kernel.org Cc: songmuchun@bytedance.com, tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, arnd@arndb.de, baolin.wang@linux.alibaba.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Date: Tue, 10 May 2022 11:46:00 +0800 Message-Id: <730ea4b6d292f32fb10b7a4e87dad49b0eb30474.1652147571.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: X-Rspamd-Queue-Id: 5D4D714009A X-Stat-Signature: pou3b17dm5uxw5ho3o3hrh1ptzb3b8h6 Authentication-Results: imf23.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf23.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.57 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1652154388-116038 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On some architectures (like ARM64), it can support CONT-PTE/PMD size hugetlb, which means it can support not only PMD/PUD size hugetlb: 2M and 1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page size specified. When unmapping a hugetlb page, we will get the relevant page table entry by huge_pte_offset() only once to nuke it. This is correct for PMD or PUD size hugetlb, since they always contain only one pmd entry or pud entry in the page table. However this is incorrect for CONT-PTE and CONT-PMD size hugetlb, since they can contain several continuous pte or pmd entry with same page table attributes, so we will nuke only one pte or pmd entry for this CONT-PTE/PMD size hugetlb page. And now try_to_unmap() is only passed a hugetlb page in the case where the hugetlb page is poisoned. Which means now we will unmap only one pte entry for a CONT-PTE or CONT-PMD size poisoned hugetlb page, and we can still access other subpages of a CONT-PTE or CONT-PMD size poisoned hugetlb page, which will cause serious issues possibly. So we should change to use huge_ptep_clear_flush() to nuke the hugetlb page table to fix this issue, which already considered CONT-PTE and CONT-PMD size hugetlb. We've already used set_huge_swap_pte_at() to set a poisoned swap entry for a poisoned hugetlb page. Meanwhile adding a VM_BUG_ON() to make sure the passed hugetlb page is poisoned in try_to_unmap(). Signed-off-by: Baolin Wang Reviewed-by: Muchun Song Reviewed-by: Mike Kravetz --- mm/rmap.c | 39 ++++++++++++++++++++++----------------- 1 file changed, 22 insertions(+), 17 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 4e96daf..219e287 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1528,6 +1528,11 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, if (folio_test_hugetlb(folio)) { /* + * The try_to_unmap() is only passed a hugetlb page + * in the case where the hugetlb page is poisoned. + */ + VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage); + /* * huge_pmd_unshare may unmap an entire PMD page. * There is no way of knowing exactly which PMDs may * be cached for this mm, so we must flush them all. @@ -1562,28 +1567,28 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, break; } } + pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); } else { flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); - } - - /* - * Nuke the page table entry. When having to clear - * PageAnonExclusive(), we always have to flush. - */ - if (should_defer_flush(mm, flags) && !anon_exclusive) { /* - * We clear the PTE but do not flush so potentially - * a remote CPU could still be writing to the folio. - * If the entry was previously clean then the - * architecture must guarantee that a clear->dirty - * transition on a cached TLB entry is written through - * and traps if the PTE is unmapped. + * Nuke the page table entry. When having to clear + * PageAnonExclusive(), we always have to flush. */ - pteval = ptep_get_and_clear(mm, address, pvmw.pte); + if (should_defer_flush(mm, flags) && !anon_exclusive) { + /* + * We clear the PTE but do not flush so potentially + * a remote CPU could still be writing to the folio. + * If the entry was previously clean then the + * architecture must guarantee that a clear->dirty + * transition on a cached TLB entry is written through + * and traps if the PTE is unmapped. + */ + pteval = ptep_get_and_clear(mm, address, pvmw.pte); - set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); - } else { - pteval = ptep_clear_flush(vma, address, pvmw.pte); + set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); + } else { + pteval = ptep_clear_flush(vma, address, pvmw.pte); + } } /*